The technical field is microelectronic devices and methods for producing microelectronic devices. More specifically, the technical field is hermetic seals for microelectronic devices.
Inkjet printers are used to produce text and images on a variety of media such as paper, transparencies and labels. A typical inkjet printer uses a carriage that holds one or more ink cartridges. The ink that is to be printed on the media is forced through small holes in thermal inkjet (TIJ) chips to produce the desired text or image. Thermal inkjet chips are small crystal structures that are placed in a larger substrate to provide the desired array of inkjet printing nozzles. The chips include an interconnect to route signals from a front side of the substrate to a backside of the substrate.
The ink used in many inkjet printers is corrosive, and the interconnect and the materials used to form the substrate may be subject to failure due to the corrosive effect of the ink. Adhesives may be used to fill the peripheral gaps between the TIJ chips and the substrate, and may prevent the flow of ink between the TIJ chips and the substrate. Adhesives may also provide some protection for other components in an inkjet printer. Adhesives, however, have several disadvantages. One disadvantage is that conventional adhesives may corrode when exposed to ink. Conventional adhesives also fail to provide a hermetic seal, and may allow ink to pass into and through the peripheral gaps.
A need therefore exists for a corrosion resistant hermetic seal between a chip and a substrate.
According to a first aspect, a carrier includes chips hermetically sealed within pockets in a substrate. A chip is hermetically sealed to the substrate by depositing seal material in a peripheral gap between the chip and the substrate. The seal is deposited between the chip and the substrate using localized energy supplied at the peripheral gap. The chips may be, for example, thermal inkjet (TIJ) chips.
According to the first aspect, the deposited seal may be generally resistant to inks used in inkjet printers, and to other corrosive substances. The deposited seal is more stable than adhesive seals. In addition, the hermetic seal prevents corrosive ink from affecting delicate wiring or other fixtures on the chips and on the substrate.
Also according to the first aspect, the use of localized energy reduces the chance that carrier components will be damaged by the deposition process. For example, if the localized energy is localized heating at the peripheral gap, the heating can be maintained in a controlled area. Therefore, wiring, fixtures, or other components on the carrier are not unnecessarily exposed to the heat energy used in the deposition process.
Other aspects and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.